In a large skillet, heat the vegetable oil over medium-high heat.
Add the diced chicken thighs to the skillet and cook until browned, about 5-7 minutes.
Stir in the minced ginger and garlic, and cook for another 1-2 minutes until fragrant.
In a small bowl, whisk together the soy sauce, honey, rice vinegar, sesame oil, and crushed red pepper flakes (if using).
Pour the sauce over the chicken in the skillet and stir to combine. Allow it to simmer for 5-10 minutes, until the chicken is cooked through and the sauce thickens slightly.
Remove from heat and fold in the shredded carrots and bell pepper, mixing well.
To assemble the lettuce cups, spoon the teriyaki chicken mixture into the center of each lettuce leaf.
Top with chopped green onions and sprinkle with sesame seeds for added texture and flavor.
Notes
Feel free to adjust the spice level by adding more or less crushed red pepper flakes.